/* 
 * Copyright 2006-2015 www.anyline.org
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 *          
 */

package org.anyline.util;

import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.codec.binary.Base64;

public class AESUtil {

	private static final String KEY_ALGORITHM = "AES";
	private static final String DEFAULT_CIPHER_ALGORITHM = "AES/ECB/PKCS5Padding";// 默认的加密算法

	/**
	 * AES 加密操作
	 * 
	 * @param content
	 *            待加密内容
	 * @param password
	 *            加密密码
	 * @return 返回Base64转码后的加密数据
	 */
	public static String encrypt(String content, String password) {
		try {
			Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);// 创建密码器
			byte[] byteContent = content.getBytes("utf-8");
			cipher.init(Cipher.ENCRYPT_MODE, getSecretKey(password));// 初始化为加密模式的密码器
			byte[] result = cipher.doFinal(byteContent);// 加密
			return Base64.encodeBase64String(result);// 通过Base64转码返回
		} catch (Exception ex) {
			Logger.getLogger(AESUtil.class.getName()).log(Level.SEVERE, null, ex);
		}
		return null;
	}

	/**
	 * AES 解密操作
	 * 
	 * @param content
	 * @param password
	 * @return
	 */
	public static String decrypt(String content, String password) {
		try {
			// 实例化
			Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);
			// 使用密钥初始化，设置为解密模式
			cipher.init(Cipher.DECRYPT_MODE, getSecretKey(password));
			// 执行操作
			byte[] result = cipher.doFinal(Base64.decodeBase64(content));
			return new String(result, "utf-8");
		} catch (Exception ex) {
			Logger.getLogger(AESUtil.class.getName()).log(Level.SEVERE, null, ex);
		}
		return null;
	}

	/**
	 * 生成加密秘钥
	 * 
	 * @return
	 */
	private static SecretKeySpec getSecretKey(final String password) {
		// 返回生成指定算法密钥生成器的 KeyGenerator 对象
		KeyGenerator kg = null;
		try {
			kg = KeyGenerator.getInstance(KEY_ALGORITHM);
			// AES 要求密钥长度为 128
			kg.init(128, new SecureRandom(password.getBytes()));
			// 生成一个密钥
			SecretKey secretKey = kg.generateKey();
			return new SecretKeySpec(secretKey.getEncoded(), KEY_ALGORITHM);// 转换为AES专用密钥
		} catch (NoSuchAlgorithmException ex) {
			Logger.getLogger(AESUtil.class.getName()).log(Level.SEVERE, null, ex);
		}
		return null;
	}

}